The UK is home to more than 10,000 “ultra-high net worth individuals” – people with assets of £20m or more – with only the US and Germany having higher numbers, says a new report.

The study from the research firm WealthInsight, based in London, predicts that the number of 10,400 or so such individuals in the UK will rise to nearly 12,000 by 2018.

The finding puts Britain ahead of China and Switzerland, which are said to be home to 8,500 and 5,500 of super-rich individuals respectively, but well behind the US, which accounts for more than 40,000. Germany has 12,100.

An ultra-high net worth individual is defined as someone with a wealth of $30m (£20m) or more, a sum including business interests, investments and property, but excluding a main home.

The figures come days after Oxfam published research showing that the share of the world’s wealth owned by the richest 1% of the planet’s population had increased from 44% in 2009 to 48% in 2014, and was set to exceed 50% by 2016.

WealthInsight said the wealthy individuals represented just 1% of the global population of people worth at least $1m, but accounted for about 33% of their total wealth. Other countries with relatively high concentrations of super-rich individuals include Canada (4,300), Brazil (4,200) and Australia (2,800).

“Despite the world’s geopolitical risks, oil price upheaval and macro-economic risks in the world economy, the global market size of [very wealthy people] is projected to grow. The super-rich usually know how to play in all market conditions,” said Roselyn Lekdee, an analyst at the firm.

The report found that while almost nine in 10 of the UK’s individuals were aged 45 or more and often had inherited their fortunes through family businesses, those in emerging economies tended to be younger and to have created their own wealth through entrepreneurship.

The dominance of ageing ultra-high net worth individuals is expected to decline over the next 10 years as more people transfer their wealth to the younger generation. Targeting the children of the super-rich, therefore, has become a key strategy for private banks and wealth management firms, such as Barclays’ wealth management arm, according to the research company, which runs a database of these individuals.